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    动物医学合辑Veterninary Medicine

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    Insights into African swine fever virus immunoevasion strategies
    WANG Jun, SHI xin-jin, SUN Hai-wei, CHEN Hong-jun
    2020, 19 (1): 11-22.   DOI: 10.1016/S2095-3119(19)62762-0
    Abstract89)      PDF in ScienceDirect      
    African swine fever (ASF) is an acute and highly contagious disease that causes severe economic losses to the swine industry.  ASF is caused by infection of African swine fever virus (ASFV) in domestic pigs, leading to almost 100% mortality.  However, no effective vaccines and pharmacologic treatment against ASF are available.  ASF poses a severe threat to the swine industry and the economy.  Here we summarize potential virus-host cell interaction mechanisms involving the suppression of innate and adaptive immune responses to ASFV entry and infection.  These mechanisms include modulation of apoptosis, inhibition of inflammatory responses, reduction of IFN production, inhibition of autophagy, and suppression of MHC-I expression.  Insights into immunoevasion strategies by ASFV may shed light on the development of vaccines, as well as preventive and therapeutic drugs.
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    Lactate dehydrogenase: An important molecule involved in acetamizuril action against Eimeria tenella
    LIU Li-li, FEI Chen-zhong, DONG Hui, ZHANG Ke-yu, Fu Jian-jun, LI Tao, XUE Fei-qun
    2020, 19 (5): 1332-1339.   DOI: 10.1016/S2095-3119(19)62845-5
    Abstract97)      PDF in ScienceDirect      
    Lactate dehydrogenase (LDH), a vital enzyme in anaerobic glycolysis, is closely associated with the survival of parasites.  Previous studies of some parasites have shown that LDH exhibits unique physicochemical properties and molecular structures and may be an ideal potential target for diagnosis and drug screening.  In this study, we aimed to investigate the effects of acetamizuril, a novel anticoccidial compound, on LDH in the second-generation merozoites of Eimeria tenella (mz-LDH).  Quantitative real-time PCR, Western blot, immunofluorescence and enzyme activity assays were each applied to detect the changes of mz-LDH.  Our results indicated that the mRNA and protein levels of mz-LDH were reduced upon acetamizuril treatment.  Immunolocalization of mz-LDH demonstrated that considerable amount of mz-LDH was distributed around or in the nuclei of second-generation merozoites within the untreated group; in contrast, the acetamizuril-treated group had very low level of mz-LDH.  Meanwhile, LDH enzyme activity assay suggested that a decreased LDH enzyme activity in both cytoplasm and nucleus of merozoites in the acetamizuril-treated group.  Moreover, the induced apoptosis in second-generation merozoites by the acetamizuril was evaluated by detecting caspase 3 activity, and acetamizuril was found to significantly increase caspase 3 activity.  The above findings show that LDH may play an important role in the mediating the activity of acetamizuril against coccidiosis, and further investigation into this aspect might contribute to new light on the pathogenesis of E. tenella during its interaction with acetamizuril.
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    Molecular detection of virulence genes in Campylobacter species isolated from livestock production systems in South Africa
    Bongekile NGOBESE, Oliver Tendayi ZISHIRI, Mohamed Ezzat EL ZOWALATY
    2020, 19 (6): 1656-1670.   DOI: 10.1016/S2095-3119(19)62844-3
    Abstract102)      PDF in ScienceDirect      
    Campylobacter species are a major cause of foodborne bacterial infections in both developed and developing countries worldwide.  Campylobacter jejuni is responsible for the majority of infections.  This study was conducted to identify virulence-associated genes in Campylobacter species isolated from livestock production systems in South Africa.  A total of 250 fecal samples consisting of cattle (n=50), chickens (n=50), goats (n=50), sheep (n=50) and pigs (n=50) were randomly collected from livestock in Eastern Cape and KwaZulu-Natal provinces of South Africa between April and October 2018.  The samples were analyzed for the presence of virulence genes in Campylobacter species using molecular PCR-based methods.  It was found that 77 and 23% of Campylobacter jejuni and Campylobacter coli respectively were isolated from all the livestock samples.  There were positive significant (P<0.05) correlations amongst all the virulence genes that were investigated.  Chi-square and Fisher’s exact tests were implemented to test for the effect of livestock species on the presence or absence of virulence genes.  The study demonstrated that most of livestock species can potentially cause zoonotic infections and food poisoning due to the high prevalence of Campylobacter.  The high prevalence of virulence genes highlights the significance of Campylobacter in livestock production systems in South Africa.  This requires the implementation of one-health approaches to reduce the impact of foodborne and zoonotic diseases for the welfare of human and animal health.
     
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    A protective role of resveratrol against the effects of immobilization stress in corpora lutea of mice in early pregnancy
    Saif ULLAH, Sheeraz MUSTAFA, Wael ENNAB, Muhammad JAN, Muhammad SHAFIQ, Ngekure M. X. KAVITA, Lü Zeng-peng, MAO Da-gan, SHI Fang-xiong
    2020, 19 (7): 1857-1866.   DOI: 10.1016/S2095-3119(19)62856-X
    Abstract102)      PDF in ScienceDirect      
    In the present study, we aimed to investigate a protective role for resveratrol against the effects of immobilization stress on corpora lutea (CL) of mice in early pregnancy.  A total of 45 early-pregnant mice were divided into no immobilization stress (NIS) group, immobilization stress (IS) group, and immobilization and resveratrol treatment (IS+RES) group (n=15).  Mice were immobilized in plastic tubes (50 mL) for 3 h per day during day 1 to 7 of pregnancy.  In the IS+RES group, 5 mg kg–1 d–1 of resveratrol was administered just prior to application of stress.  We analyzed apoptotic activity in CL by Western blotting analysis (WB), transmission electron microscopy (TEM), and immunohistochemistry (IHC).  Serum progesterone levels were examined with radioimmunoassay (RIA).  IHC results showed that the intensity of positive staining for Bax was increased, and for Bcl-2 was decreased in CL after IS, while resveratrol treatment reversed the positive staining for Bax and Bcl-2.  WB revealed that immobilization stress up-regulated the expression of Bax and caspase-9, and down-regulated Bcl-2 expression, while resveratrol treatment attenuated the effects of immobilization stress on the expression of Bax, Bcl-2 and caspase-9.  According to our TEM results, apoptosis as defined by chromatin condensation was found in CL after immobilization stress, while resveratrol inhibited the apoptosis.  We also demonstrated that immobilization stress decreased progesterone concentrations and ovarian expression of StAR, while resveratrol restored the concentrations of progesterone and expression of StAR back to normal.  These results indicated that immobilization stress induced luteal regression while resveratrol inhibited luteal regression, suggesting that resveratrol plays a protective role on corpora lutea of mice during early pregnancy.
     
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    The circulation of unique reassortment strains of infectious bursal disease virus in Pakistan
    Altaf HUSSAIN, WU Tian-tian, FAN Lin-jin, WANG Yu-long, Farooq Khalid MUHAMMAD, JIANG Nan, GAO Li, LI Kai, GAO Yu-long, LIU Chang-jun, CUI Hong-yu, PAN Qing, ZHANG Yan-ping, Asim ASLAM, Khan MUTI-UR-REHMAN, Muhammad Imran ARSHAD, Hafiz Muhammad ABDULLAH, WANG Xiao-mei, QI Xiao-le
    2020, 19 (7): 1867-1875.   DOI: 10.1016/S2095-3119(20)63183-5
    Abstract144)      PDF in ScienceDirect      
    Infectious bursal disease (IBD), caused by IBD virus (IBDV), is one of the most devastating and immunosuppressive diseases of the poultry and has been a constraint on the sustainable poultry production around the globe including Pakistan.  While the disease is threatening the poultry industry, the nature of predominant strains of IBDV in Pakistan remained ill-defined.  In this study, an epidemiology survey was conducted in the main chicken-farming regions of Pakistan.  The batch of Pakistan IBDVs genes simultaneously covering both VP1 and VP2 were amplified, sequenced, and analyzed.  The unique segment-reassortant IBDVs (vv-A/Uniq-B), carrying segment A from vvIBDV and segment B from one unique ancestor, were identified as one important type of circulating strains in Pakistan.  The data also discovered the characteristic molecular features of Pakistan IBDVs, which will contribute to scientific vaccine selection and effective prevention of the disease.
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    Alphaherpesvirus-vectored vaccines against animal diseases: Current progress
    HU Yang, WANG Ming-shu, CHENG An-chun, JIA Ren-yong, YANG Qiao, WU Ying, LIU Ma-feng, ZHAO Xin-xin, ZHU De-kang, CHEN Shun, ZHANG Sha-qiu, WANG Yin, GAO Qun, OU Xu-min, MAO Sai, WEN Xing-jian, XU Zhi-wen, CHEN Zheng-li, ZHU Ling, LUO Qi-hui, TIAN Bin, PAN Lei-chang, Mujeeb Ur REHMAN, LIU Yun-ya, YU Yan-ling, ZHANG Ling, CHEN Xiao-yue
    2020, 19 (8): 1928-1940.   DOI: 10.1016/S2095-3119(20)63175-6
    Abstract203)      PDF in ScienceDirect      
    Recombinant virus-vectored vaccines are novel agents that can effectively activate specific and nonspecific immunity, are multivalent and multieffective, and have high safety ratings.  Animal alphaherpesviruses have a large genome, contain multiple nonessential regions that do not affect viral replication and are capable of accepting the insertion of an exogenous gene and expressing the antigen protein.  Furthermore, animal alphaherpesviruses have a wide host spectrum, can replicate in the host and continuously stimulate the animal to produce immunity to the corresponding pathogen, thus making them ideal carriers for recombinant virus-vectored vaccines.  With the development of gene-editing technology, recombinant viruses capable of expressing foreign genes can be constructed by various methods.  Currently, studies on recombinant virus-vectored vaccines constructed based on animal alphaherpesviruses have involved poultry, pigs, cattle, sheep, and companion animals.  Studies have shown that the construction of recombinant animal alphaherpesviruses enables the acquisition of immunity to multiple diseases.  This article mainly summarizes the current progress on animal alphaherpesvirus-vectored vaccines, aiming to provide reference for the development of new animal alphaherpesvirus-vectored vaccines.
     
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    Protective efficacy of an H5/H7 trivalent inactivated vaccine produced from Re-11, Re-12, and H7-Re2 strains against challenge with different H5 and H7 viruses in chickens
    ZENG Xian-ying, CHEN Xiao-han, MA Shu-jie, WU Jiao-jiao, BAO Hong-mei, PAN Shu-xin, LIU Yan-jing, DENG Guo-hua, SHI Jian-zhong, CHEN Pu-cheng, JIANG Yong-ping, LI Yan-bing, HU Jing-lei, LU Tong, MAO Sheng-gang, GUO Xing-fu, LIU Jing-li, TIAN Guo-bin, CHEN Hua-lan
    2020, 19 (9): 2294-2300.   DOI: 10.1016/S2095-3119(20)63301-9
    Abstract163)      PDF in ScienceDirect      
    We developed an H5/H7 trivalent inactivated vaccine by using Re-11, Re-12, and H7-Re2 vaccine seed viruses, which were generated by reverse genetics and derived their HA genes from A/duck/Guizhou/S4184/2017(H5N6) (DK/GZ/S4184/17) (a clade 2.3.4.4d virus), A/chicken/Liaoning/SD007/2017(H5N1) (CK/LN/SD007/17) (a clade 2.3.2.1d virus), and A/chicken/Guangxi/SD098/2017(H7N9) (CK/GX/SD098/17), respectively.  The protective efficacy of this novel vaccine and that of the recently used H5/H7 bivalent inactivated vaccine against different H5 and H7N9 viruses was evaluated in chickens.  We found that the H5/H7 bivalent vaccine provided solid protection against the H7N9 virus CK/GX/SD098/17, but only 50–60% protection against different H5 viruses.  In contrast, the novel H5/H7 trivalent vaccine provided complete protection against the H5 and H7 viruses tested.  Our study underscores the importance of timely updating of vaccines for avian influenza control.
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    Rapid detection of Pseudomonas aeruginosa by cross priming amplification
    XIANG Yong, YAN Ling, ZHENG Xiao-cui, LI Li-zhen, LIU Peng, CAO Wei-sheng
    2020, 19 (10): 2523-2529.   DOI: 10.1016/S2095-3119(20)63187-2
    Abstract91)      PDF in ScienceDirect      
    Pseudomonas aeruginosa (PA) is an opportunistic pathogen of humans and animals and a common source of nosocomial infections especially of the respiratory tract.  Pseudomonas aeruginosa is also a major bacterial disease of poultry and in particular, eggs and newly hatched chicks.  In this study, we developed a simple, accurate and rapid molecular detection method using cross priming amplification (CPA) with a nucleic acid test strip to detect P. aeruginosa.  The assay efficiently amplified the target gene within 45 min at 62°C only using a simple water bath.  The detection limit of the method was 1.18×102 copies μL–1 for plasmid DNA and 4.4 CFU mL–1 for bacteria in pure culture, and was 100 times more sensitive than conventional PCR.  We screened 83 clinical samples from yellow-feather broiler breeder chickens and hospitalized/treated dogs and cats using CPA, PCR and traditional culture methods.  The positive-sample ratios were 15.3% (13/83) by CPA, 13.3% (11/83) by PCR and 12.1% (10/83) by the culture method.  The established CPA method has significant advantages for detecting P. aeruginosa.  The method is easy to use and possesses high specificity and sensitivity without the requirements of complicated experimental equipment.  The PA-CPA assay is especially fit for outdoor and primary medical units and is an ideal system for the rapid detection and monitoring of P. aeruginosa.
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    Detection of antimicrobial resistance and virulence-related genes in Streptococcus uberis and Streptococcus parauberis isolated from clinical bovine mastitis cases in northwestern China
    ZHANG Hang, YANG Feng, LI Xin-pu, LUO Jin-yin, WANG Ling, ZHOU Yu-long, YAN Yong, WANG Xu-rong, LI Hong-sheng
    2020, 19 (11): 2784-2791.   DOI: 10.1016/S2095-3119(20)63185-9
    Abstract99)      PDF in ScienceDirect      
    The objectives of this study were to investigate antimicrobial resistance of Streptococcus uberis and Streptococcus parauberis isolated from cows with bovine clinical mastitis in China and to examine the distribution of resistance- and virulence-related gene patterns.  Antimicrobial susceptibility was determined by the E-test.  Genes encoding antimicrobial resistance and invasiveness factors were examined by PCR.  A total of 27 strains were obtained from 326 mastitis milk samples.  Streptococcus parauberis isolates (n=11) showed high resistance to erythromycin (90.9%), followed by tetracycline (45.5%), chloramphenicol (36.4%) and clindamycin (27.3%).  Streptococcus uberis isolates (n=16) were highly resistant to tetracycline (81.3%) and clindamycin (62.5%).  Both species were susceptible to ampicillin.  The most prevalent resistance gene in S. uberis was tetM (80.0%), followed by blaZ (62.5%) and ermB (62.5%).  However, tetM, blaZ, and ermB genes were only found in 27.3, 45.5, and 27.3%, respectively, of S. parauberis.  In addition, all of the isolates carried at least one selected virulence-related gene.  The most prevalent virulence-associated gene pattern in the current study was sua+pauA/skc+gapC+hasC detected in 22.2% of the strains.  One S. uberis strain carried 7 virulence-associated genes and belonged to the sua+pauA/skc+gapC+cfu+hasA+hasB+hasC pattern.  More than 59.3% of analysed strains carried 4 to 7 virulence-related genes.  Our findings demonstrated that S. parauberis and S. uberis isolated from clinical bovine mastitis cases in China exhibited diverse molecular ecology, and that the strains were highly resistant to antibiotics commonly used in the dairy cow industry.  The data obtained in the current study contribute to a better understanding of the pathogenesis of bacteria in mastitis caused by these pathogens, and the findings are relevant to the development of multivalent vaccines and targeted prevention procedures.
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    An improved scheme for infectious bursal disease virus genotype classification based on both genome-segments A and B
    WANG Yu-long, FAN Lin-jin, JIANG Nan, GAO Li, LI Kai, GAO Yu-long, LIU Chang-jun, CUI Hong-yu, PAN Qing, ZHANG Yan-ping, WANG Xiao-mei, QI Xiao-le
    2021, 20 (5): 1372-1381.   DOI: 10.1016/S2095-3119(20)63424-4
    Abstract87)      PDF in ScienceDirect      
    Infectious bursal disease (IBD) is caused by infectious bursal disease virus (IBDV), which has a genome consisting of two segments of double-stranded linear RNA.  IBDVs have been traditionally divided into four phenotypes based on their pathogenicity and antigenicity, including classic, variant, very virulent, and attenuated IBDV.  With the emergences of divergent molecular characteristics of novel strains produced by continuous mutations and recombination, it is increasingly difficult to define new IBDV strains using the traditional descriptive classification method.  The most common classification scheme for IBDV with segmented genome is based solely on segment A, while the significance of segment B has been largely neglected.  In this study, an improved scheme for IBDV genotype classification based on the molecular characteristics of both VP2 (a viral capsid protein encoded by segment A) and VP1 (an RNA-dependent RNA polymerase protein encoded by segment B) was proposed for the first time.  In this scheme, IBDV was classified into nine genogroups of A and five genogroups of B, respectively; the genogroup A2 was further divided into four lineages.  The commonly used phenotypic classifications of classic, variant, very virulent, and attenuated IBDVs correspond to the A1B1, A2B1, A3B2, and A8B1 genotypes of the proposed classification scheme.  The novel variant IBDVs including the strains identified in this study were classified as belonging to genotype A2dB1.  The flexibility and versatility of this improved classification scheme will allow the unambiguous identification of existing and emerging IBDV strains, which will greatly facilitate molecular epidemiology studies of IBDV.
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    Evaluation of a povidone-iodine and chitosan-based barrier teat dip in the prevention of mastitis in dairy cows
    ZHANG Hui-min, JIANG Hong-rui, CHEN Dai-jie, SHEN Zi-liang, MAO Yong-jiang, LIANG Yu-sheng, Juan J. LOOR, YANG Zhang-ping
    2021, 20 (6): 1615-1625.   DOI: 10.1016/S2095-3119(20)63418-9
    Abstract98)      PDF in ScienceDirect      
    Postmilking teat dip is an important tool used to prevent mastitis in the modern dairy industry.  In this study, we evaluated the in vitro and in vivo efficacies of a barrier teat dip containing povidone-iodine and chitosan for the prevention of mastitis.  In experiment 1, we evaluated the antibacterial effects of chitosans with different molecular weights against six mastitis-causing bacteria based on the minimal inhibitory concentration test.  The results showed that 50 kDa chitosan had the maximum antibacterial activity compared with 5, 150 and 350 kDa chitosans.  In experiment 2, the inhibition zone test indicated that the barrier teat dip with 4.0% povidone-iodine and 1.0% chitosan had higher (P<0.05) in vitro antibacterial efficacy against most tested mastitis-causing bacteria than the barrier teat dip with 4.0% povidone-iodine and no chitosan.  In experiments 3 and 4, we evaluated the efficacies of two postmilking teat dips, 1) a barrier teat dip containing 1.0% chitosan and 4.0% povidone-iodine and 2) a conventional nonbarrier product containing 10% povidone-iodine in a field trial at two commercial dairy herds (1 and 2).  A 56-d split-udder experiment (experiment 3) was conducted using 47 lactating Chinese Holstein cows in herd 1.  Both left teats were immersed in barrier postmilking dip, and both right teats were dipped with nonbarrier postmilking dip.  During a 56-d split-herd experiment (experiment 4), a total of 139 lactating Chinese Holstein cows from herd 2 were allocated to two groups: 1) all teats of 67 cows were dipped in the nonbarrier teat dip, and 2) all teats of 72 cows were dipped in the barrier teat dip.  Milk samples were collected and analyzed for somatic cell count (SCC), fat content, protein content, and fat-to-protein ratio prior to the start of sampling (0 d), and at 28 and 56 d after initiation.  Bacteriological analysis was only performed on milk samples with SCC≥200?000 cells mL–1.  In experiment 3, no differences (P>0.05) in SCC, somatic cell score (SCS) or other milk quality indicators were observed between nonbarrier and barrier teat dip treatment teats throughout the experiment.  At the end of experiment 4, compared with nonbarrier teat dip group, a reduction (P<0.05) of 29% was observed for subclinical mastitis infection prevalence in the barrier teat dip group.  In the barrier teat dip group, the subclinical mastitis infection prevalence on 56 d was lower (P<0.05) than 0 d.  No differences (P>0.05) in milk qualities or clinical mastitis incidence were detected between groups.  Bacteriological analysis demonstrated that the barrier product containing povidone-iodine and chitosan reduced the subclinical mastitis infection prevalence induced by mastitis pathogens.  This effect was mainly due to the reductions in Klebsiella pneumoniae, Pseudomonas aeruginosa, and Escherichia fergusonii infections.  Overall, the data indicated that a barrier teat dip containing 4% povidone-iodine and 1% chitosan was more effective than 10% povidone-iodine in preventing subclinical mastitis. 
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    Susceptibility breakpoint for cefquinome against Escherichia coli and Staphylococcus aureus from pigs
    ZHANG Hui-lin, ZHAO Yi-yang, ZHOU Zi-chong, DING Huan-zhong
    2021, 20 (7): 1921-1932.   DOI: 10.1016/S2095-3119(20)63572-9
    Abstract83)      PDF in ScienceDirect      
    Cefquinome is the only fourth-generation cephalosporin used solely for veterinary applications.  In this study, we established the wild-type cut-off (COWT) and pharmacokinetic/pharmacodynamic cut-off (COPD) of cefquinome against Escherichia coli and Staphylococcus aureus.  A total of 210 E. coli and 160 S. aureus isolates were collected from pigs in Guangdong Province between 2014 and 2018.  The minimum inhibitory concentrations (MICs) were determined using a microdilution broth method.  MIC50 and MIC90 were 0.06 and 0.25 μg mL–1 for E. coli and 0.5 and 1 μg mL–1 for S. aureus, respectively.  Statistical analysis and the ECOFFinder Program showed that the COWT for cefquinome against E. coli and S. aureus were 0.125 and 2 µg mL–1, respectively.  The resistance rates were 11.9% for E. coli and 6.25% for S. aureus.  Based on a 5 000-subject Monte Carlo simulation, the COPD value for cefquinome against E. coil and S. aureus was 0.25 µg mL–1 under the recommended dose (2 mg kg–1, twice a day for 3 days), confirming that infections caused by strains with MIC≤0.25 μg mL–1 could be effectively treated.  Following adjustment of the dosing regimen to 4.5 mg kg–1, effective treatment (>90) was achieved for S. aureus infections with MIC90 1 μg mL–1.  This susceptibility breakpoint determination is significant for resistant surveillance and cefquinome dosage guidance against E. coli and S. aureus in pigs.
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    Kaempferol inhibits Pseudorabies virus replication in vitro through regulation of MAPKs and NF-κB signaling pathways
    CHEN Xu, CHEN Ya-qin, YIN Zhong-qiong, WANG Rui, HU Huai-yue, LIANG Xiao-xia, HE Chang-liang, YIN Li-zi, YE Gang, ZOU Yuan-feng, LI Li-xia, TANG Hua-qiao, JIA Ren-yong, SONG Xu
    2021, 20 (8): 2227-2239.   DOI: 10.1016/S2095-3119(20)63477-3
    Abstract155)      PDF in ScienceDirect      
    Pseudorabies virus (PRV), in the family Herpesviridae, is a pathogen of Aujeszky’s disease, which causes great economic losses to the pig industry.  Recent outbreaks of Pseudorabies imply that new control measures are urgently needed.  The present study shows that kaempferol is a candidate drug for controlling PRV infection, as it possesses the ability to inhibit PRV replication in a dose-dependent manner in vitro.  Kaempferol at a concentration of 52.40 μmol L–1 could decrease PRV-induced cell death by 90%.  With an 50% inhibitory concentration (IC50) value of 25.57 μmol L–1, kaempferol was more effective than acyclovir (positive control) which has an IC50 value of 54.97 μmol L–1.  A mode of action study indicated that kaempferol inhibited viral penetration and replication stages, decreasing viral loads by 4- and 30-fold, respectively.  Addition of kaempferol within 16 h post infection (hpi) could significantly inhibit virus replication, and viral genome copies were decreased by almost 15-fold when kaempferol was added at 2 hpi.  Kaempferol regulated the NF-κB and MAPKs signaling pathways involved in PRV infection and changed the levels of the target genes of the MAPKs (ATF-2 and c-Jun) and NF-κB (IL-1α, IL-1β and IL-2) signaling pathways.  The findings of the current study suggest that kaempferol could be an alternative measure to control PRV infection.
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    Detection of arboviruses in Culicoides (Diptera: Ceratopogonidae) collected from animal farms in the border areas of Yunnan Province, China
    DI Di, LI Chen-xi, LI Zong-jie, WANG Xin, XIA Qi-qi, Mona SHARMA, LI Bei-bei, LIU Ke, SHAO Dong-hua, QIU Ya-feng, Soe-Soe WAI, YANG Shi-biao, WEI Jian-chao, MA Zhi-yong
    2021, 20 (9): 2491-2501.   DOI: 10.1016/S2095-3119(21)63613-4
    Abstract133)      PDF in ScienceDirect      
    Biting midges of the genus Culicoides (order Diptera, family Ceratopogonidae) are potential biological vectors for the transmission of certain arboviruses among humans, livestock, and wild animals.  This study collected a total of 405 Culicoides individuals from seven animal farms located in five counties in the border areas of Yunnan Province, China, and examined the Culicoides species composition and the major arboviruses carried by the Culicoides species.  The collected Culicoides were classified into seven species with variable abundances: Culicoides arakawae (5.43%, 22/405), Culicoides homotomus (1.23%, 5/405), Culicoides obsoletus (19.75%, 80/405), Culicoides orientalis (17.28%, 70/405), Culicoides oxystoma (29.38%, 119/405), Culicoides peregrinus (5.68%, 23/405), and Culicoides nipponensis (21.23%, 86/405).  Among the seven species, C. oxystoma and C. nipponensis were distributed in all the five counties with abundances of 13.33–44.87% and 10.00–46.83%, respectively, suggesting that these were the dominant species of Culicoides widespread on animal farms in the border areas.  PCR was used to detect major arboviruses in the collected Culicoides specimens, including bluetongue virus (BTV), Japanese encephalitis virus, Dengue virus, Zika virus, African swine fever virus, and African horse sickness virus.  Among the tested viruses, only BTV serotype 1 was tested positive in C. oxystoma specimens collected from a buffalo farm.  Culicoides oxystoma was the dominant species on animal farms in the sampled areas, but it has not previously been documented as positive for BTV in China.  The current results thus suggest that C. oxystoma could be an important vector for BTV transmission in these border areas, which, however, needs to be confirmed by further comprehensive experiments.  Overall, the present study provides the first profile of Culicoides species on animal farms in the China, Vietnam, and Myanmar border areas, establishes the prevalence of arboviruses carried by these Culicoides species, and suggests the vector potential of C. oxystoma species for the transmission of BTV. 
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    Viricidal activity of several disinfectants against African swine fever virus
    JIANG Cheng-gang, SUN Ying, ZHANG Fan, AI Xin, FENG Xiao-ning, HU Wei, ZHANG Xian-feng, ZHAO Dong-ming, BU Zhi-gao, HE Xi-jun
    2021, 20 (11): 3084-3088.   DOI: 10.1016/S2095-3119(21)63631-6
    Abstract102)      PDF in ScienceDirect      
    Prevention of African swine fever, a disease caused by African swine fever virus (ASFV), requires maintenance of high biosecurity standards, which principally relies on disinfection.  Finding the perfect disinfectant against ASFV is difficult because of the lack of relevant data.  Therefore, we aimed to find the most effective disinfectant and to optimise its concentration as well as contact time to confirm the viricidal effect against ASFV in vitro.  We evaluated the viricidal activity of three concentrations each of six common disinfectants against ASFV using immersion disinfection assay (IDA) and spray disinfection assay (SDA); the concentrations of these disinfectants at which complete viral inactivation occurred were almost same as the manufacturer-recommended concentrations, but the exposure times for viral inactivation are different.  The following disinfectants (assay: concentration, exposure time) showed complete inactivation: iodine and acid mixed solution (IDA/SDA: 0.5%, 10 min); compound potassium peroxymonosulfate (IDA: 0.25%, 30 min; SDA: 0.25%, 60 min); citric acid (IDA: 0.25%, 60 min; SDA: 0.5%, 60 min); sodium dichloroisocyanurate (IDA: 0.125%, 60 min; SDA: 0.25%, 60 min); and glutaral ang deciquam (IDA/SDA: 0.2%, 60 min); and deciquam (IDA/SDA: 0.5%, 60 min).  However, in the presence of organic material contamination, disinfectants did not show a marked inactivation effect.  Therefore, disinfection procedures should be performed in two steps: thorough mechanical cleaning followed by application of disinfectant.  In conclusion, all the tested disinfectants can inactivate ASFV; these can be used as alternative disinfectants to enhance biosecurity.
     
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    Detection and characterization of Hepatitis E virus from commercial rabbit livers in Hebei, China
    XIAO Peng, TIAN Ji-jing, MAO Jing-jing, GUO Zhao-jie, ZHAO Yue, LIU Tian-long, CHEN Jian, WANG Tong-tong, MA Long-huan, SHE Rui-ping
    2021, 20 (12): 3270-3276.   DOI: 10.1016/S2095-3119(21)63632-8
    Abstract127)      PDF in ScienceDirect      

    Rabbit hepatitis E virus (HEV) has been reported for years and is thought to have the potential for zoonotic transmission from rabbits to humans.  As reported, HEV genotype 3 (gt3) is the most prevalent form of HEV in rabbits.  To determine the prevalence of HEV in commercial rabbit livers, 176 liver samples were collected from an abattoir in Hebei Province, China.  Three (1.7%) samples tested positive for RNA of HEV-ORF2 (open reading frames-2).  Sequence analysis showed that the three isolates shared high identities with each other (94.08–98.85%).  Further analysis showed that all the rabbit strains clustered together in the branch of HEV gt3.  Further study by immunohistochemistry (IHC) assays showed that 131 (74.4%) liver samples were positive for HEV ORF2 protein.  Pathological changes including cell degeneration, inflammatory cell infiltration and bile duct epithelial cell hyperplasia were observed under microscopy.  These findings indicated the presence of HEV in commercial livers of rabbits.  Additional studies should be conducted to investigate the infectivity of rabbit HEV (rHEV) and the potential risks of zoonotic transmission of rHEV from rabbits to human beings.

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